This invention is an improvement over existing labeling apparatus, such as that shown in my prior U.S. Pat. No. 4,108,710 granted Aug. 22, 1978.
In such machines, a continuous strip of label material is gripped and pulled at its leading edge by a rotating label transport drum, and an individual label is severed therefrom by cutting means located ahead of the drum. Transverse ridges or projections on the label transport drum press the label against a glue applicator and then press the leading edge of the label against a container. The label is then released and wrapped around the container. The label transport drum is generally made of metal with an outer sleeve of an elastomer, perforated over its surface so that a vacuum can be pulled through the surface to grip the labels. When worn, the complete drum must be replaced, and this can be quite costly.
In many labeling operations, the label is wrapped completely around the container so that the trailing edge overlaps the leading edge. In such cases, it would be desirable to use one type of glue at the leading edge that is particularly adapted to adhere the label to the material of the container and another glue type at the trailing edge that would be better adapted to adhere the two overlapping portions of the label together. However, fixed radial projections on the vacuum drum, tend to press the label against both glue wheels, and it is not practical to use two separate glues unless the glue strip for the leading edge of the label is applied directly to the container before the label is applied.
It is further desirable that steps be taken to prevent contact between the glue wheel and the vacuum drum when there is no label present to accept the glue. In present machines, it is customary to pivot the glue applying apparatus away from the label transport drum in absence of a label. However, at the high speed operations common in container labeling machines, e.g. 750 containers per minute, the rapid movement of the relatively heavy gluing apparatus is difficult to accomplish and requires substantial bearing mountings.